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Commit 707a6e46 authored by Josh Gao's avatar Josh Gao
Browse files

adb: libusb: replace sleep with timed CV wait. 

Instead of sleeping for 500ms at the end of every device poll loop, use
a timed condition variable wait so that we can tell the device poll
thread to immediately commit suicide.

Bug: http://b/37869663
Test: adb kill-server; adb start-server
Change-Id: I597071866f7d9ef91900411727345d32c1a97556
parent 84606f86

adb/client/usb_libusb.cpp

+13 −4
Original line number Diff line number Diff line
@@ -152,7 +152,9 @@ static auto& usb_handles = *new std::unordered_map<std::string, std::unique_ptr< 
static auto& usb_handles_mutex = *new std::mutex();



static std::thread* device_poll_thread = nullptr;

static std::atomic<bool> terminate_device_poll_thread(false);

static bool terminate_device_poll_thread = false;

static auto& device_poll_mutex = *new std::mutex();

static auto& device_poll_cv = *new std::condition_variable();



static std::string get_device_address(libusb_device* device) {

    return StringPrintf("usb:%d:%d", libusb_get_bus_number(device),
@@ -376,7 +378,7 @@ static void process_device(libusb_device* device) { 
static void poll_for_devices() {

    libusb_device** list;

    adb_thread_setname("device poll");

    while (!terminate_device_poll_thread) {

    while (true) {

        const ssize_t device_count = libusb_get_device_list(nullptr, &list);



        LOG(VERBOSE) << "found " << device_count << " attached devices";
@@ -389,7 +391,10 @@ static void poll_for_devices() { 


        adb_notify_device_scan_complete();



        std::this_thread::sleep_for(500ms);

        std::unique_lock<std::mutex> lock(device_poll_mutex);

        if (device_poll_cv.wait_for(lock, 500ms, []() { return terminate_device_poll_thread; })) {

            return;

        }

    }

}
@@ -412,7 +417,11 @@ void usb_init() { 
    // TODO: Use libusb_hotplug_* instead?

    device_poll_thread = new std::thread(poll_for_devices);

    android::base::at_quick_exit([]() {

        {

            std::unique_lock<std::mutex> lock(device_poll_mutex);

            terminate_device_poll_thread = true;

        }

        device_poll_cv.notify_all();

        device_poll_thread->join();

    });

}